I don't have time right now to read the complete article, but it surely
is amazing what you can do to silence your PC! I now virtually have to stop breathing to hear mine and I can only recommend to invest in silence than always in the fastest, newest PC.
I think the noisiest part of my case are the two 120mm casefans - but that's a steady, low-pitch hum, so it doesn't annoy me
-f0dder
Here's what you can do:
- there's a small piece of hardware available that reduces the fanspeed based on the temperature of the passing airflow
- there are special silent fans available where you only hear the airflow, not the actual fan

The harddrive-rotation-induced resonance is the most annoying part, since it's a "cyclic" sound.
-f0dder
I highly suggest some decoupling device (and of course the quiet Samsung HDs), I rarely hear my HDs anymore.
